Joint timing and frequency synchronization based on weighted CAZAC sequences for reduced-guard-interval CO-OFDM systems

摘要

A novel joint symbol timing and carrier frequency offset (CFO) estimationalgorithm is proposed for reduced-guard-interval coherent optical orthogonalfrequency-division multiplexing (RGI-CO-OFDM) systems. The proposed algorithmis based on a constant amplitude zero autocorrelation (CAZAC) sequence weightedby a pseudo-random noise (PN) sequence. The symbol timing is accomplished byusing only one training symbol of two identical halves, with the weightingapplied to the second half. The special structure of the training symbol isalso utilized in estimating the CFO. The performance of the proposed algorithmis demonstrated by means of numerical simulations in a 115.8-Gb/s 16-QAMRGI-CO-OFDM system.